1. Field of the Invention
The present invention relates to a multi-layer plastic pipe for use in a cooling water system, and a manufacturing method therefor.
2. Description of the Related Art
The conventional technology of a plastic pipe is disclosed in JP No. 11-300844A. The plastic pipe is constituted by laminating an outer layer comprising a polyamide resin to an inner layer. A resin material of the inner layer is made of a PPS resin including a polyphenylene sulfide or an denatured aromatic polysulfide resin, and a polyamide resin (nylon 6 or the like). In this plastic pipe, resistance to an antifreeze solution, which has ethylene glycol as its main constituent, is exhibited by the PPS resin in the inner layer, and adhesiveness relative to the outer layer is heightened by adding a polyamide resin to the inner layer.
However, the conventional plastic pipe does not achieve sufficient durability relative to resistance capabilities of the antifreeze solution while ensuring adhesiveness between the inner layer and outer layer.